/*
 * jdapistd.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains application interface code for the decompression half
 * of the JPEG library.  These are the "standard" API routines that are
 * used in the normal full-decompression case.  They are not used by a
 * transcoding-only application.  Note that if an application links in
 * jpeg_start_decompress, it will end up linking in the entire decompressor.
 * We thus must separate this file from jdapimin.c to avoid linking the
 * whole decompression library into a transcoder.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Forward declarations */
LOCAL boolean output_pass_setup JPP((j_decompress_ptr cinfo));


/*
 * Decompression initialization.
 * jpeg_read_header must be completed before calling this.
 *
 * If a multipass operating mode was selected, this will do all but the
 * last pass, and thus may take a great deal of time.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL          boolean jpeg_start_decompress(j_decompress_ptr cinfo)
{
	if(cinfo->global_state == DSTATE_READY)
	{
		/* First call: initialize master control, select active modules */
		jinit_master_decompress(cinfo);
		if(cinfo->buffered_image)
		{
			/* No more work here; expecting jpeg_start_output next */
			cinfo->global_state = DSTATE_BUFIMAGE;
			return TRUE;
		}
		cinfo->global_state = DSTATE_PRELOAD;
	}
	if(cinfo->global_state == DSTATE_PRELOAD)
	{
		/* If file has multiple scans, absorb them all into the coef buffer */
		if(cinfo->inputctl->has_multiple_scans)
		{
#ifdef D_MULTISCAN_FILES_SUPPORTED
			for(;;)
			{
				int             retcode;

				/* Call progress monitor hook if present */
				if(cinfo->progress != NULL)
					(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
				/* Absorb some more input */
				retcode = (*cinfo->inputctl->consume_input) (cinfo);
				if(retcode == JPEG_SUSPENDED)
					return FALSE;
				if(retcode == JPEG_REACHED_EOI)
					break;
				/* Advance progress counter if appropriate */
				if(cinfo->progress != NULL && (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS))
				{
					if(++cinfo->progress->pass_counter >= cinfo->progress->pass_limit)
					{
						/* jdmaster underestimated number of scans; ratchet up one scan */
						cinfo->progress->pass_limit += (long)cinfo->total_iMCU_rows;
					}
				}
			}
#else
			ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif							/* D_MULTISCAN_FILES_SUPPORTED */
		}
		cinfo->output_scan_number = cinfo->input_scan_number;
	}
	else if(cinfo->global_state != DSTATE_PRESCAN)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	/* Perform any dummy output passes, and set up for the final pass */
	return output_pass_setup(cinfo);
}


/*
 * Set up for an output pass, and perform any dummy pass(es) needed.
 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
 * Exit: If done, returns TRUE and sets global_state for proper output mode.
 *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
 */

LOCAL           boolean output_pass_setup(j_decompress_ptr cinfo)
{
	if(cinfo->global_state != DSTATE_PRESCAN)
	{
		/* First call: do pass setup */
		(*cinfo->master->prepare_for_output_pass) (cinfo);
		cinfo->output_scanline = 0;
		cinfo->global_state = DSTATE_PRESCAN;
	}
	/* Loop over any required dummy passes */
	while(cinfo->master->is_dummy_pass)
	{
#ifdef QUANT_2PASS_SUPPORTED
		/* Crank through the dummy pass */
		while(cinfo->output_scanline < cinfo->output_height)
		{
			JDIMENSION      last_scanline;

			/* Call progress monitor hook if present */
			if(cinfo->progress != NULL)
			{
				cinfo->progress->pass_counter = (long)cinfo->output_scanline;
				cinfo->progress->pass_limit = (long)cinfo->output_height;
				(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
			}
			/* Process some data */
			last_scanline = cinfo->output_scanline;
			(*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, &cinfo->output_scanline, (JDIMENSION) 0);
			if(cinfo->output_scanline == last_scanline)
				return FALSE;	/* No progress made, must suspend */
		}
		/* Finish up dummy pass, and set up for another one */
		(*cinfo->master->finish_output_pass) (cinfo);
		(*cinfo->master->prepare_for_output_pass) (cinfo);
		cinfo->output_scanline = 0;
#else
		ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif							/* QUANT_2PASS_SUPPORTED */
	}
	/* Ready for application to drive output pass through
	 * jpeg_read_scanlines or jpeg_read_raw_data.
	 */
	cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
	return TRUE;
}


/*
 * Read some scanlines of data from the JPEG decompressor.
 *
 * The return value will be the number of lines actually read.
 * This may be less than the number requested in several cases,
 * including bottom of image, data source suspension, and operating
 * modes that emit multiple scanlines at a time.
 *
 * Note: we warn about excess calls to jpeg_read_scanlines() since
 * this likely signals an application programmer error.  However,
 * an oversize buffer (max_lines > scanlines remaining) is not an error.
 */

GLOBAL          JDIMENSION jpeg_read_scanlines(j_decompress_ptr cinfo, JSAMPARRAY scanlines, JDIMENSION max_lines)
{
	JDIMENSION      row_ctr;

	if(cinfo->global_state != DSTATE_SCANNING)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	if(cinfo->output_scanline >= cinfo->output_height)
	{
		WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
		return 0;
	}

	/* Call progress monitor hook if present */
	if(cinfo->progress != NULL)
	{
		cinfo->progress->pass_counter = (long)cinfo->output_scanline;
		cinfo->progress->pass_limit = (long)cinfo->output_height;
		(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
	}

	/* Process some data */
	row_ctr = 0;
	(*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
	cinfo->output_scanline += row_ctr;
	return row_ctr;
}


/*
 * Alternate entry point to read raw data.
 * Processes exactly one iMCU row per call, unless suspended.
 */

GLOBAL          JDIMENSION jpeg_read_raw_data(j_decompress_ptr cinfo, JSAMPIMAGE data, JDIMENSION max_lines)
{
	JDIMENSION      lines_per_iMCU_row;

	if(cinfo->global_state != DSTATE_RAW_OK)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	if(cinfo->output_scanline >= cinfo->output_height)
	{
		WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
		return 0;
	}

	/* Call progress monitor hook if present */
	if(cinfo->progress != NULL)
	{
		cinfo->progress->pass_counter = (long)cinfo->output_scanline;
		cinfo->progress->pass_limit = (long)cinfo->output_height;
		(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
	}

	/* Verify that at least one iMCU row can be returned. */
	lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
	if(max_lines < lines_per_iMCU_row)
		ERREXIT(cinfo, JERR_BUFFER_SIZE);

	/* Decompress directly into user's buffer. */
	if(!(*cinfo->coef->decompress_data) (cinfo, data))
		return 0;				/* suspension forced, can do nothing more */

	/* OK, we processed one iMCU row. */
	cinfo->output_scanline += lines_per_iMCU_row;
	return lines_per_iMCU_row;
}


/* Additional entry points for buffered-image mode. */

#ifdef D_MULTISCAN_FILES_SUPPORTED

/*
 * Initialize for an output pass in buffered-image mode.
 */

GLOBAL          boolean jpeg_start_output(j_decompress_ptr cinfo, int scan_number)
{
	if(cinfo->global_state != DSTATE_BUFIMAGE && cinfo->global_state != DSTATE_PRESCAN)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	/* Limit scan number to valid range */
	if(scan_number <= 0)
		scan_number = 1;
	if(cinfo->inputctl->eoi_reached && scan_number > cinfo->input_scan_number)
		scan_number = cinfo->input_scan_number;
	cinfo->output_scan_number = scan_number;
	/* Perform any dummy output passes, and set up for the real pass */
	return output_pass_setup(cinfo);
}


/*
 * Finish up after an output pass in buffered-image mode.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL          boolean jpeg_finish_output(j_decompress_ptr cinfo)
{
	if((cinfo->global_state == DSTATE_SCANNING || cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image)
	{
		/* Terminate this pass. */
		/* We do not require the whole pass to have been completed. */
		(*cinfo->master->finish_output_pass) (cinfo);
		cinfo->global_state = DSTATE_BUFPOST;
	}
	else if(cinfo->global_state != DSTATE_BUFPOST)
	{
		/* BUFPOST = repeat call after a suspension, anything else is error */
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
	}
	/* Read markers looking for SOS or EOI */
	while(cinfo->input_scan_number <= cinfo->output_scan_number && !cinfo->inputctl->eoi_reached)
	{
		if((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
			return FALSE;		/* Suspend, come back later */
	}
	cinfo->global_state = DSTATE_BUFIMAGE;
	return TRUE;
}

#endif							/* D_MULTISCAN_FILES_SUPPORTED */
